Traditional manufacturing systems use customer orders and marketing forecasts to predict the quantity of product needed at any given time. This process is based upon scheduled batch manufacturing techniques where products are created based upon a weekly or monthly schedule. Usually these products are produced as subassemblies or fabricated parts which are scheduled based upon the monthly requirement of the finished products. These subassemblies are then assembled into the final product to fill the customer orders, or placed into finished goods.
Formalized computer systems have been developed to assist in the traditional scheduling and tracking of these batch subassemblies or fabricated parts, as well as buying the required raw material. These systems are called Manufacturing Resource Planning (MRP) systems. The prevailing manufacturing methodology in the Far East, commonly referred to by the adopting Japanese as Kanban Flow Manufacturing, is often called Just-In-Time (JIT) by western manufacturers.
In traditional batch manufacturing, raw material is ordered well in advance and kept in a storeroom. Once the assembly or fabricated part is scheduled, a work order is released, and the parts required to produce the assembly are issued based upon a planned start date and start quantity. Subassembly parts are often produced in the same manner as the final product, thus, after being produced, the subassemblies are stored until they are needed for a final assembly. Because of the length of the process, a large inventory of finished goods is often needed to satisfy a fluctuating customer demand. This schedulized manufacturing makes customer responsiveness very slow.
The number of days that it takes to complete a product from the time the first, lowest-level, manufactured component or subassembly is produced until the final product is shipped is called the manufacturing lead time. A long lead time, caused by the subassembly manufacturing techniques, makes it difficult to react quickly to changing customer demand. The lengthy process of long manufacturing lead times, queues for each subassembly, and frequent trips to the storeroom place a long period of time between the customer's order and manufacturing's completion of that order.
One of the more significant problems caused by this process is that the production schedule is created well in advance, and cannot be altered easily. Because of this, the software used in this process also lacks the ability to easily adjust schedules. If the manufacturing process is to become more flexible, the system software used for scheduling must also become more flexible. In the traditional system, however, the production quantity, or total demand, is manually set by a master scheduler, and cannot easily be adjusted.
It is thus apparent that there is a need in the art for an improved method or apparatus which automatically determines the total demand on a daily basis. There is a further need in the art for such a system that can automatically adjust the demand, within customer supplied limits, to allow the quantity to vary for future dates. The present invention meets these and other needs.